Drastic enhancement in critical temperature in Ag doped GdBa2Cu3O7-δ.

The substitution of Ag in high temperature superconductor (HTS) affects both granular and intergranular properties. However, the substitution in underdoped of Ag in GdBa₂Cu₃O_7-δ (GBCO) is very complex in nature. To understand the impact microscopically it is important to use a suitable GBCO without Ag. We have chosen such a system with very low critical temperature of 18.2 K. We have studied transport properties of several Ag doped GdBa₂Cu₃O_7-δ. A drastic enhancement of the critical temperature has been observed. Using three dimensional Aslamazov-Larkin (AL) equation we have extracted the coherence length. An increase in the coherence length in order of magnitude has been observed with a maximum coherence length of 9.8 nm in GdBa₂Cu₂.7Ag_0.3O_7-δ. Variation of the superfluid phase stiffness becomes affected as a result of which such an enhancement in critical temperature may not be impossible. [ABSTRACT FROM AUTHOR]